Our company uses AdSense, and we have not been disabled so far. Our monthly revenues are much larger than Hatchling's. We have user-generated content. Despite our MOST extensive, multi-tier keyword-based content screening system, we are terrorized by Google weekly, from noreply address, that AdSense ads are disabled on this or that user's page, due to various violations found (often in the content in obscure languages, e.g. Hungarian , Finnish, Turkish), threatening to shut down the whole account. We are aware that the account can be shut down at any moment, and have been diversifying our ad revenue component for the last couple of years, using CasaleMedia, TribalFusion, Adbrite, taking conscious cuts in ad revenue compared to AdSense in exchange for security. Those companies actually care about your revenue.
DO NOT RELY on ADSENSE as a sole revenue provider for your startup! Do not! AdSense is only a good idea either if your revenue is negligible, or if you are a highly public high profile client like MySpace, where they KNOW that they cannot get away without serious negative PR.